What is baroreceptor sensitivity?

The baroreflex or baroreceptor sensitivity (BRS) index is a measurement to quantify how much control the baroreflex has on the heart rate. BRS can be valuable in assessing the development and progression of cardiovascular diseases. Reduced BRS Can Indicate: Neurological Disorders.

How does phenylephrine increase blood pressure?

Phenylephrine is a selective α1-adrenergic receptor agonist that increases blood pressure mainly by increasing systemic vascular resistance, without an associated increase in myocardial contractility.

What happens when baroreflex sensitivity increases?

The baroreflex elicits reciprocal responses of the autonomic nervous system: when afferent baroreflex nerve traffic intensifies (this happens when BP increases), the efferent sympathetic traffic decreases, while the efferent parasympathetic traffic increases. The inverse response occurs when BP lowers.

How do I increase baroreceptor sensitivity?

Slow breathing at 6 breaths/min increases baroreflex sensitivity and reduces sympathetic activity and chemoreflex activation, suggesting a potentially beneficial effect in hypertension.

What do the baroreceptors regulate?

Baroreceptor exerts control of mean arterial pressure as a negative feedback loop. Nerve impulses from arterial baroreceptors are tonically active; increases in arterial blood pressure will result in an increased rate of impulse firing.

How does phenylephrine mechanism of action?

Phenylephrine works by directly stimulating alpha-1 adrenergic receptors in the arteries causing vasoconstriction (narrowing of the blood vessels). This reduces nasal congestion by preventing fluid from draining from the blood vessels into the tissues lining the nasal passages.

What is the role of phenylephrine?

Phenylephrine is used to relieve nasal discomfort caused by colds, allergies, and hay fever. It is also used to relieve sinus congestion and pressure. Phenylephrine will relieve symptoms but will not treat the cause of the symptoms or speed recovery.

How does the baroreflex work?

The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure causes the heart rate to decrease. Decreased blood pressure decreases baroreflex activation and causes heart rate to increase and to restore blood pressure levels.

What causes baroreflex failure?

The underlying causes of baroreflex failure included the familial paraganglioma syndrome, neck surgery or radiation therapy for pharyngeal carcinoma, bilateral lesions of the nucleus tractus solitarii, and surgical section of the glossopharyngeal nerves; in two patients the cause was unknown.

What are the effects of exercise training programs on baroreflex function?

Exercise training improves baroreflex control of HR during the increase and decrease of BP in spontaneously hypertensive rats. Furthermore, these studies indicate that the improvement in baroreflex sensitivity is, in part, mediated by the enhancement of the aortic depressor nerve sensitivity.

What action occurs when the aortic and carotid baroreceptors are stimulated?